It is conventional to investigate the characteristics of downhole fluids contained in underground formations by taking samples and analyzing the samples in a laboratory or in situ. In particular, downhole fluid characteristics may include partial densities of one or more compounds in the downhole fluid.
Some methods and apparatuses utilize spectrometers to determine a partial density of one or more compounds in the downhole fluid. For example, measured downhole fluid spectra may exhibit absorption peaks associated with the presence of a compound. Absorption peak amplitudes may be used to determine the partial density of the compound. Descriptions of methods or apparatuses for determining the partial density of one or more compounds in downhole fluid may be found, for example, in U.S. Pat. Nos. 7,336,356; 7,362,422; and 7,456,958; U.S. Patent Application Pub. No. 2008/0078544; and PCT Patent Application Pub. No. 2007/143474, the disclosures of which are incorporated herein by reference.
In some cases, absorption peak amplitudes may be biased by factors other than the absorption by the compound associated with the absorption peak. It may be desirable to account for the bias when determining the partial density of the compound. Examples of such methods are described in U.S. Pat. Nos. 6,992,768; and 7,095,012; and U.S. Patent Application Pub. No. 2008/0173445, the disclosures of which are incorporated herein by reference.